1. Field of the Invention
The present invention generally relates to hydrokinetic torque coupling devices, and more particularly to a hydrokinetic torque coupling device including a turbine-piston lock-up clutch for mechanically coupling driving and driven shafts, and epicyclic gearing.
2. Description of the Related Art
Generally, vehicles with automatic transmissions are equipped with a hydrokinetic torque coupling device for fluidly coupling the driving shaft of an engine to a driven shaft of a transmission. Lockup clutches are known for mechanically coupling the driving and driven shafts. Lock-up clutches are described in, for example, U.S. Pat. No. 8,276,723 and U.S. Pat. No. 7,191,879.
Typically, a hydrokinetic torque coupling device includes a casing, a hydrodynamic torque converter, a torsional vibration damper and a lock-up clutch provided for locking the torque converter. The torque converter includes an impeller connected to a driving shaft through the casing, a turbine axially fixed relative to the impeller and configured to be rotationally connected to a driven shaft, and a stator.
The casing includes a front casing shell and a rear casing shell fixedly interconnected together. Typically, the front casing shell is coupled to and rotatably driven by an internal combustion engine, while the rear casing shell serves as an impeller shell of the impeller and is adjacent to a vehicular transmission. In other words, conventionally, the impeller is on a transmission side, while the turbine is on an engine side.
However, torque coupling devices are known having the impeller and turbine reversed, i.e., wherein the impeller on the engine side and the turbine is on the transmission side. Such a reverse torque coupling device is described in, for example, KR 10-1311531. In such reverse torque coupling devices, a normally hollow stationary stator shaft is replaced by a solid shaft within a hollow rotating transmission input shaft. Conversely, a normally solid transmission input shaft is replaced by a hollow shaft rotating about a solid stationary stator shaft. This reversal of shaft configuration creates shaft support issues for the transmission.
While hydrokinetic torque coupling devices with lock-up clutches have proven to be acceptable for vehicular driveline applications and conditions, improvements that may enhance their performance and cost are possible. For example, it would be beneficial to reverse the impeller and turbine while maintaining the standard transmission interface in which the stationary stator shaft is hollow and the transmission input shaft is solid and extends within the hollow stationary stator shaft. As another example of an improvement, it would be beneficial to reduce the spatial requirements of components of the hydrokinetic torque coupling device and/or to consolidate functions of two or more components into a single component.